A man shot and killed by an FBI agent in Orlando early Wednesday killed three people along with Boston Marathon bombing suspect Tamerlan Tsarnaev in 2011, sources tell NBC News.+Watch: Interview with man's friend

On Tuesday morning, officials said a special agent and two Massachusetts State Police troopers were interviewing Ibragim Todashev, 27, regarding his connections to Tomerlan Tsarnaev. Todashev, was originally cooperative, but he was shot after attacking the agent, the FBI said.

In an interview in Chechnya with NBC news, Todashev's father, Abdul-Baki Todashev, said he regrets ever letting his son come to the United States.

Sources said Todashev and Tsarnaev killed three men in Waltham, Mass., in 2011 after ripping them off for drugs because they did not want the men to later identify them.

The father told NBC News that his son had nothing to do with the slayings.

"I can say with 100 percent confidence that my son was not guilty of anything," Abdul-Baki Todashev said.

Investigators said Todashev confessed to the FBI that he played a role in the slayings.

Officials said the FBI's shooting review team from Washington, D.C., are still in the process of piecing together the circumstances of the shootingat the Windhover Condominiums on Kirkman Road near Conroy Road.